The present invention relates to an improved hydrocarbon conversion process which utilizes a regenerable zeolite-containing catalyst to process a hydrocarbon feed which has been treated to reduce the fluoride content therein to below 100 ppb.
It is a common practice in the hydrocarbon and petrochemical industry to treat feedstocks, products, and intermediates in order to purify streams or to remove deleterious components from hydrocarbon streams. Hydrocarbon feedstocks and intermediate process streams are often purified to increase process efficiency. That is, it is much more efficient to process reactant hydrocarbons than it is to include refractory hydrocarbons or hydrocarbons which lead to undesirable products in a catalyzed hydrocarbon process. Hydrocarbon reaction products are often purified or otherwise treated to enhance the products value, stability, and so forth.
Additionally, impurities in hydrocarbons being processed in a catalytic system have been recognized as having a negative effect on catalyst stability and conversion. For example, cracking catalysts are poisoned by metals such as nickel, vanadium, and sodium which originate in the hydrocarbon feed to a cracking unit. Treatment of such a feed to remove or passivate such metals is well known to increase the useful life of cracking catalysts. In another example, sulfur accumulation on a reforming catalyst promotes undesirable cracking reactions. The treatment of reformer feeds to remove sulfur components is a well known method of maintaining process efficiency and protecting catalyst stability.
In the case of a hydrocarbon conversion process utilizing a regenerable zeolite-containing catalyst, it is well known that regeneration procedures which expose a zeolite-containing catalyst to steam severely effects the performance of the zeolite catalyst following regeneration. This performance loss, observed even under mild regeneration conditions, is typically not totally recoverable. Therefore, processes and methods to suppress zeolite activity loss in a hydrocarbon conversion process employing a regenerable zeolite are quite important in extending the useful life and thus the economic viability of such a process.
It has now been surprisingly found that if a hydrocarbon feed is first treated to reduce its fluoride content to below 100 ppb that the use of such a hydrocarbon feed in a hydrocarbon conversion process utilizing a regenerable zeolite will result in a higher retention of catalyst activity of the regenerated catalyst. The improvement being longer catalyst life expectancy because of the zeolite-containing catalysts greater resistance to activity loss during catalyst regeneration.